Safety and Effectiveness of Mechanical Thrombectomy From the Fully Enrolled Multicenter, Prospective CLOUT Registry

Rationale and design of the DEFIANCE study: A randomized controlled trial of mechanical thrombectomy versus anticoagulation alone for iliofemoral deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a common medical condition that is associated with clinically significant sequelae, including postthrombotic syndrome (PTS). Anticoagulation alone remains the guideline-recommended treatment for many patients with iliofemoral DVT. Recent technological advances have led to an increase in the use of mechanical thrombectomy for DVT, but mechanical thrombectomy-based procedures have not yet been compared with standard-of-care anticoagulation therapy in randomized studies.

METHODS

The DEFIANCE study (ClinicalTrials.gov: NCT05701917) is an international and actively enrolling randomized controlled trial (RCT) in lower extremity DVT assessing an interventional strategy that includes mechanical thrombectomy with the ClotTriever System (Inari Medical, Irvine, CA) versus anticoagulation alone. Approximately 300 patients with unilateral iliofemoral DVT and symptom duration ≤ 12 weeks will be randomized 1:1. Study conduct includes an independent core laboratory for duplex ultrasound assessment, an independent medical monitor for safety adjudication, and evaluation of PTS severity on the Villalta scale using best clinical practices. The primary endpoint is a composite outcome structured as a hierarchal win ratio of 1) the occurrence of treatment failure or therapy escalation as adjudicated by the medical monitor, with failure defined as amputation or gangrene of the target leg or venous thromboembolism-related mortality, and 2) the assessment of PTS severity at the 6-month follow-up visit. In addition to being a component of the primary endpoint, the severity of PTS at 6 months is also evaluated as a stand-alone secondary endpoint. An additional secondary endpoint is a composite of outcomes at the 10-day visit and is structured as a hierarchal win ratio of 1) vessel compressibility on duplex ultrasound, 2) patient-reported pain, and 3) improvement of edema. The safety endpoints are access site complications requiring endovascular or surgical repair and the occurrence through the 30-day visit of mortality, major bleeding, or new symptomatic pulmonary embolism.

CONCLUSIONS

DEFIANCE will be the first RCT to evaluate a mechanical thrombectomy-based interventional approach versus anticoagulation therapy alone for DVT. The results will inform the treatment of patients with iliofemoral DVT and the prevention of PTS-associated morbidity.

TRIAL REGISTRATION

DEFIANCE: RCT of ClotTriever System Versus Anticoagulation In Deep Vein Thrombosis (DEFIANCE), ClinicalTrials.gov: NCT05701917, URL: https://clinicaltrials.gov/study/NCT05701917?cond=Deep%20Vein%20Thrombosis&term=defiance&rank=1.

DETECT-DVT: Detroit Evaluation of Thrombectomy and Evaluation of Intravascular Ultrasound in Deep Vein Thrombosis

Background

We sought to evaluate the use of intravascular ultrasound (IVUS) and mechanical thrombectomy (MT) for the treatment of deep vein thrombosis (DVT) in a community hospital setting.

Methods

Data were analyzed among patients with lower extremity DVT who underwent MT from December 1, 2021 to December 1, 2022.

Results

A total of 1263 patients were evaluated and only 8.8% of patients with DVT received intervention. Of them, 42% were women. The mean age and length of stay were 61.3 years and 3.5 days, respectively. For cases that proceeded to intervention, IVUS was used in 89% of cases, 80% received venoplasty, and 30% received stents. The mean number of MT passes was 4 and the mean contrast volume used was 71 mL. Flow was restored in 96.7% of cases. The procedure was unable to be completed in 1.8% of the cases, and 1.8% had a reported complication after the procedure. Vascular surgery was consulted in 64.4% of the cases, cardiology in 33%, interventional radiology in 12.5%, and 10.9% of the patients had multiple consults. MT was associated with postprocedure reduction of hemoglobin levels (13.4 vs 12.1; P < .001) and no change in postprocedure creatinine levels (1.08 vs 1.04; P = .28). IVUS was associated with fewer passes, although this was not statistically significant (P = .09). Additionally, IVUS was associated with increased stenting (P = .03) and venoplasty (P < .001).

Conclusions

MT is shown to be successful in restoring venous flow and is utilized by multiple specialties in the treatment of DVT. Additionally, IVUS was widely used in conjunction with MT, and it was associated with increased advanced interventions, such as venoplasty and stent placement.

Initial experience with the ambulatory management of acute iliofemoral deep vein thrombosis with May-Thurner syndrome with percutaneous mechanical thrombectomy, angioplasty and stenting

OBJECTIVE

Patients undergoing intervention for acute iliofemoral deep vein thrombosis (IFDVT) with May-Thurner syndrome (MTS) typically require inpatient (IP) hospitalization for initial treatment with anticoagulation and management with pharmacomechanical thrombectomy. Direct oral anticoagulants and percutaneous mechanical thrombectomy (PMT) devices offer the opportunity for outpatient (OP) management. We describe our approach with these patients.

METHODS

Patients receiving intervention for acute IFDVT from January 2020 through October 2022 were retrospectively reviewed. Patients undergoing unilateral thrombectomy, venous angioplasty, and stenting for IFDVT with MTS comprised the study population and were divided into two groups: (1) patients admitted to the hospital and treated as IPs and (2) patients who underwent therapy as OPs. The two groups were compared regarding demographics, risk factors, procedural success, complications, and follow-up.

RESULTS

A total of 92 patients were treated for IFDVT with thrombectomy, angioplasty, and stenting of whom 58 comprised the IP group and 34 the OP group. All 92 patients underwent PMT using the Inari ClotTriever (Inari Medical), intravascular ultrasound, angioplasty, and stenting with 100% technical success. Three patients in the IP group required adjuvant thrombolysis. There was no difference in primary patency of the treated IFDVT segment at 12 months between the two groups (IP, 73.5%; OP, 86.7%; P = .21, log-rank test).

CONCLUSIONS

Patients with acute IFDVT and MTS deemed appropriate for thrombectomy and iliac revascularization can be managed with initiation of ambulatory direct oral anticoagulant therapy and subsequent return for ambulatory PMT, angioplasty, and stenting. This approach avoids the expense of IP care and allows for effective use of resources at a time when staffing and supply chain shortages have led to inefficiencies in the provision of IP care for nonemergent conditions.

Treating hemodialysis access thrombosis with the InThrill Thrombectomy System: Technique and case report

The purpose of this report is to describe via a case example an efficient mechanical thrombectomy technique for hemodialysis access thrombosis using the InThrill Thrombectomy System (Inari Medical, Irvine, CA). A man in his late 60s with end-stage renal disease and a thrombosed femoral arteriovenous graft (AVG) underwent a thrombectomy procedure to remove all thrombotic material including the arterial plug and restore use of the graft for hemodialysis. The InThrill Thrombectomy System used in this procedure consists of a mechanical thrombectomy catheter with a wall-apposing coring element and a sheath with a retractable funnel and aspiration port. The technique starts with gaining wire and sheath access towards the venous outflow. The InThrill Thrombectomy catheter is deployed proximal to the sheath to sequentially remove small segments of thrombus thus avoiding sheath obstruction. A locking syringe is used for rapid aspiration, reducing or eliminating the need to remove the InThrill sheath with every mechanical thrombectomy pass. Finally, the arterial plug is pulled using a Fogarty balloon sheath (Edwards Lifesciences, Irvine, CA) and extracted using the InThrill catheter, removing what may be the nidus for recurrent AV access thrombosis. The technique described here provided a means to remove all thrombotic material including the arterial plug in a planned, sequential manner, without the need for thrombolytics. Patency was restored to the patient's femoral AVG within 60 minutes, and hemodialysis resumed shortly thereafter. Further studies are needed to support long-term efficacy of this thrombolytic-free treatment option.

Comparison of anticoagulation vs mechanical thrombectomy for the treatment of iliofemoral deep vein thrombosis

OBJECTIVE

To compare the comparative effects of treatment with contemporary mechanical thrombectomy (MT) or anticoagulation (AC) on Villalta scores and post-thrombotic syndrome (PTS) incidence through 12 months in iliofemoral deep vein thrombosis (DVT).

METHODS

Patients with DVT in the Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) randomized trial and the ClotTriever Outcomes (CLOUT) registry were included in this analysis. Both studies evaluated the effects of thrombus removal on the incidence of PTS. Patients with bilateral DVT, isolated femoral-popliteal DVT, symptom duration of >4 weeks, or incomplete case data for matching covariates were excluded. Propensity scores were used to match patients 1:1 who received AC (from ATTRACT) with those treated with mechanical thrombectomy (from CLOUT) using nearest neighbor matching on nine baseline covariates, including age, body mass index, leg treated, provoked DVT, prior venous thromboembolism, race, sex, Villalta score, and symptom duration. Clinical outcomes, including Villalta score and PTS, were assessed. Logistic regression was used to estimate the likelihood of developing PTS at 12 months.

RESULTS

A total of 164 pairs were matched, with no significant differences in baseline characteristics after matching. There were fewer patients with any PTS at 6 months (19% vs 46%; P < .001) and 12 months (17% vs 38%; P < .001) in the MT treatment group. Modeling revealed that, after adjusting for baseline Villalta scores, patients treated with AC had significantly higher odds of developing any PTS (odds ratio, 3.1; 95% confidence interval, 1.5-6.2; P = .002) or moderate to severe PTS (odds ratio, 3.1; 95% confidence interval, 1.1-8.4; P = .027) at 12 months compared with those treated with MT. Mean Villalta scores were lower through 12 months among those receiving MT vs AC (3.3 vs 6.3 at 30 days, 2.5 vs 5.5 at 6 months, and 2.6 vs 4.9 at 12 months; P < .001 for all).

CONCLUSIONS

MT treatment of iliofemoral DVT was associated with significantly lower Villalta scores and a lower incidence of PTS through 12 months compared with treatment using AC. Results from currently enrolling clinical trials will further clarify the role of these therapies in the prevention of PTS after an acute DVT event.

Endovascular interventions in cancer patients with compromise of the mediastinal vasculature: a review

The mediastinal vasculature can be affected by various etiologies in cancer patients. Both direct and indirect sequela of cancer may result in life-threatening clinical presentations. Tumor growth may cause vessel narrowing and decreased blood flow from either extrinsic mass effect, invasion into the vascular wall, or tumor thrombus within the lumen. In addition, cancer patients are predisposed to indirect sequela to the mediastinal vasculature from an increased risk of benign thromboembolic events, tumor thrombus, or iatrogenic complications during cancer treatments. Benign thrombus may result in partial or complete occlusion of the superior vena cava (SVC) or pulmonary artery. Vascular damage such as pseudoaneurysm or stricture may result from iatrogenic complications from radiation therapy, surgery, or other interventions. The clinical presentation of the vascular compromise is dictated by the vascular anatomical structure that is affected and the type of injury. In the appropriate clinical scenario, endovascular treatments may be pursued. These minimally invasive procedures include balloon venoplasty and angioplasty, stent placement, catheter-directed thrombolysis, embolectomy, and embolization. This review discusses the most common endovascular interventions for vascular compromise based on the great vessel affected: the SVC, pulmonary artery, pulmonary vein, bronchial arteries, or the aorta and supra-aortic arteries. Indications for treatment are discussed, with particular attention to disease etiology and clinical presentation.

Intraprocedural Use of the Novel Protrieve Sheath Removes Embolus During Mechanical Thrombectomy of a Complex Iliocaval Deep Vein Thrombosis

Extension of proximal deep vein thrombosis (DVT) into the inferior vena cava (IVC) complicates treatment with mechanical thrombectomy, as the presence of IVC thrombus increases embolization risks. In the case of a 39-year-old man with left-sided iliocaval DVT, the novel Protrieve sheath (Inari Medical, Irvine, California) was intraprocedurally placed in the IVC to ensure such complications would not outweigh the benefits of intervention. During successful thrombectomy, the sheath's wall-apposing funnel trapped and removed procedural embolus from the IVC, with no complications occurring. Studies to determine whether the device can broadly improve the safety of complex DVT procedures are warranted.

One-Year Clinical Outcomes Following Mechanical Thrombectomy for Deep Vein Thrombosis: A CLOUT Registry Analysis

Background

Mechanical thrombectomy is a promising treatment option for deep vein thrombosis; however, long-term data are lacking. Here, we report for the first time the 1-year clinical outcomes from the completely enrolled ClotTriever Outcomes (CLOUT) registry evaluating mechanical thrombectomy with the ClotTriever System (Inari Medical).

Methods

The CLOUT registry (NCT03575364) is a prospective, multicenter, single-arm study that enrolled 500 patients with proximal lower extremity deep vein thrombosis. Prespecified 1-year outcomes include Villalta score and corresponding postthrombotic syndrome (PTS) severity, duplex ultrasound findings of patency (defined as the presence of flow with normal or partial compressibility), Revised Venous Clinical Severity Score, and quality of life (QoL).

Results

In CLOUT, the median age was 61.9 years and 50.5% of patients were women. A total of 310 patients completed the 1-year visit. The 1-year PTS rate (Villalta score ≥ 5) was 19.3% and the moderate-to-severe PTS rate (Villalta score ≥ 10) was 8.8%. Median Villalta score decreased from 9.0 (IQR, 5.0-14.0) at baseline to 1.0 (IQR, 0.0-4.0) at 1 year (P < .0001). Similar rates of PTS and moderate-to-severe PTS were observed among limbs assessed at all study time points. Patency was observed in 94.2% of limbs. Median Revised Venous Clinical Severity Score was 6.0 (IQR, 3.0-9.0) at baseline and 3.0 (IQR, 1.0-4.0) at 1 year (P < .0001). Additionally, 90.4% of patients experienced improvements in QoL.

Conclusions

One-year outcomes from the CLOUT registry demonstrate low PTS rates and preserved patency accompanied by improved symptom relief and QoL. Study follow-up through 2 years is ongoing.

Mechanical thrombectomy of venous in-stent thrombosis with the novel RevCore thrombectomy system: A report of 2 cases

In-stent thrombosis (IST) is a common venous stent complication. Acute IST warranting intervention can generally be treated with catheter-directed thrombolysis or aspiration thrombectomy. However, thrombosed stents often have chronic-appearing components that pose a significant treatment challenge as the thrombus firmly adheres to the stent and vessel wall and becomes resistant to thrombolytics and aspiration thrombectomy. Alternate treatment options such as venoplasty, stent relining, and medical management do not remove existing IST but rather remodel the lumen with limited long-term efficacy. This report details 2 cases of chronic-appearing IST successfully debulked with the novel RevCore Thrombectomy System. RevCore, designed to mechanically liberate acute to chronic IST via an expandable nitinol coring element, achieved substantial luminal gain and sustained patency in both patients.

Hemiplegia in acute ischemic stroke: A comprehensive review of case studies and the role of intravenous thrombolysis and mechanical thrombectomy

Acute ischemic stroke is a significant health concern worldwide, often leading to long-term disability and decreased quality of life. Rapid and appropriate treatment is crucial for achieving optimal outcomes in these patients. Intravenous thrombolysis (IVT) and mechanical thrombectomy (MT) are two commonly used interventions for acute ischemic stroke, but their effectiveness in improving neurological symptoms and functional outcomes in patients with hemiplegia remains uncertain. The aim of this work was to evaluate the impact of IVT and MT within a 4.5-h time frame on patients with acute ischemic stroke and hemiplegia. A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Relevant studies that assessed the impact of IVT and MT within 4.5-h on hemiplegia in patients with an acute ischemic stroke were included. Data were extracted and analyzed to determine the overall effects of these interventions. Most included case reports indicate positive outcomes in terms of neurological symptom improvement and functional recovery in patients with hemiplegia after receiving IVT and MT within the specified time frame. However, the heterogeneity among the patients and the limited use of IVT due to contraindications posed challenges in determining the most effective treatment option. The findings from the included studies demonstrate that both interventions led to a decrease in National Institutes of Health Stroke Scale scores, indicating an improvement in neurological symptoms. The results highlight the beneficial effects of early thrombolytic interventions and MT on the neurological status and functional outcomes of patients with an acute ischemic stroke.

Single-center experience with the ClotTriever BOLD catheter for deep vein thrombosis percutaneous mechanical thrombectomy of the lower extremity

Background

The ClotTriever System is a percutaneous mechanical thrombectomy system used to treat deep vein thrombosis (DVT). The BOLD catheter is a newer compatible component with a modified coring element for which reported outcomes are limited. This retrospective study aims to assess the preliminary procedural safety and success data for patients treated with the BOLD catheter.

Methods

All consecutive patients with symptomatic lower extremity DVT who underwent thrombectomy with the BOLD catheter between 23 November 2021 and 26 June 2022 at a single center were included. Baseline and procedural characteristics were reported. The primary outcome, intraprocedural safety, was assessed by a chart review of recorded intraprocedural adverse events (AEs) or device malfunction. The secondary outcome, procedural success, was defined as ≥75% reduction in the total occlusion across treated venous segments. This was assessed by an interventionalist review of pre- and postprocedural venograms. Additional outcomes included length of postprocedural hospital stay and assessment of AEs at discharge and a 30-day follow-up visit.

Results

Eleven patient cases were reviewed. The median patient age was 65 years, the majority were women, and all were treated unilaterally. All procedures were completed in a single session without intraprocedural AEs or device malfunction. The median procedural blood loss was 50 ml. A review of pre- and postprocedural venograms showed that 35 venous segments were treated, including the femoral (n = 9), common femoral (n = 9), external iliac (n = 10), and common iliac (n = 7) veins. Procedural success was achieved in 10 patients (90.9%), and the median reduction rate in venous occlusion was 100%. The median length of postprocedural hospital stay was 1 day, and no AEs were noted at discharge (N = 11). One adverse event occurred among the eight patients who completed their follow-up visit. A patient with advanced-stage cancer and medication failure had a recurrent DVT 13 days postprocedure, which was not related to the device or procedure.

Conclusions

No safety concerns concerning the BOLD catheter were raised during the review of the cases included in this analysis, and the device was successful in reducing venous occlusion in patients with symptomatic proximal lower extremity DVT.